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A003719 Expansion of tan(x)*cosh(x).
(Formerly M3996)
4
1, 5, 41, 685, 19921, 887765, 56126201, 4776869245, 526589630881, 72989204937125, 12424192360405961, 2547879762929443405, 619570064016825283441, 176273806836039238900085, 58010159408189457446855321, 21864887814006548202566779165 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
a(n) = Sum_{k>=0} binomial(2n+1, 2k)*A000111(2n+1-2k). -Philippe Deléham,Aug 27 2005
a(n) ~ cosh(Pi/2) * (2*n+1)! * 2^(2*n+3) / Pi^(2*n+2). -Vaclav Kotesovec,Feb 16 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[Cosh[x]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (*Vaclav Kotesovec,Feb 16 2015 *)
CROSSREFS
Bisection ofA009739and (apparently)A062272.
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended and formatted Mar 15 1997 byOlivier Gérard
Prior Mathematica program deleted byHarvey P. Dale,Nov 04 2019
STATUS
approved

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Last modified September 15 04:39 EDT 2024. Contains 375931 sequences. (Running on oeis4.)